COEN 4331: Network Theory
Sec: 201
Name:
Zainab Al-Mabuk 200800942
Tutorial Chapter_4
10-3-2013
Q1. Differentiate between guided media and unguided media?
In both cases, communication is in the form of electromagnetic waves.

Guided media, the waves are guided along a physical path; examples of
guided media are twisted pair, coaxial cable, and optical fiber.

Unguided media, also called wireless, provide a means for transmitting
electromagnetic waves but do not guide them; examples are propagation
through air, vacuum, and seawater.
Q2. Differentiate between an analog and digital electromagnetic signal?

An analog signal is one in which the signal intensity varies in a smooth, or
continuous, fashion over time. In other words, there are no breaks in the
signal. An analog signal is a continuously varying electromagnetic wave that
may be propagated over a variety of media, depending on spectrum

A digital signal is one in which the signal intensity maintains a constant level
for some period of time and then changes to another constant level, in a
discrete fashion. Digital data can be represented by digital signals, with a
different voltage level for each of the two binary digits.
Q3. What are three important characteristics of periodic signal?

Peak amplitude (A): the peak amplitude is the maximum value or strength of
the signal over time

Frequency (f): the frequency is the rate [in cycles per seconds

Phase: measures of the relative position in time within a single period of a
signal, as is illustrated subsequently
Q4. Define fundamental frequency?
Fundamental frequency is the lowest frequency of periodic waveform.
Q5. What is the relationship between a signal’s spectrum and its bandwidth?
2
There is a direct relationship between data rate and bandwidth: the higher the data rate of
a signal, the greater is its required effective bandwidth
Q6. What is attenuation?
The strength of a signal falls off with distance over any transmission medium.

For guided media the reduction is generally exponential and thus is
typically expressed as a constant number of decibels per unit distance.

For unguided media (wireless transmission), attenuation is a more complex
function of distance and the makeup of the atmosphere.
Q7. What key factors affect channel capacity?

Data rate

Bandwidth

Error rate
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